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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Foodborne Toxin Detection and Prevention Research » Research » Publications at this Location » Publication #365727
Research Project: Biocontrol Interventions for High-Value Agricultural Commodities

Location: Foodborne Toxin Detection and Prevention Research

Title: Aspergillus flavus NRRL 35739, a poor biocontrol agent, may have increased relative expression of stress response genes

Author
item PENNERMAN, KAYLA - Rutgers University
item YIN, GUOHUA - Rutgers University
item BENNETT, JOAN - Rutgers University
item Hua, Sui Sheng

Submitted to: The Journal of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2019
Publication Date: 6/20/2019
Citation: Pennerman, K.K., Yin, G., Bennett, J.W., Hua, S.T. 2019. Aspergillus flavus NRRL 35739, a poor biocontrol agent, may have increased relative expression of stress response genes. The Journal of Fungi. 5(2):53. https://doi.org/10.3390/jof5020053.
DOI: https://doi.org/10.3390/jof5020053

Interpretive Summary: This pilot study provides an opening into the study of how genetic factors and abiotic stress tolerance may influence competitive growth by non-aflatoxigenic strains of A. flavus. To the authors’ knowledge, there are no previously published studies on the genetics of weak aflatoxin biocontrol agents; most relevant studies focus on identifying strong biocontrol agents. It is of particular interest that NRRL 35739 is the only non-aflatoxigenic strain for which researchers note that the strain sometimes increases aflatoxin accumulation. The findings reported here provide other scientists with a starting point to further investigate how tolerance to abiotic stresses may influence competitive growth by non-aflatoxigenic strains of A. flavus. NRRL 35739 serves as a useful control for research into the largely uninvestigated factors that influence aflatoxin production when different A. flavus strains are grown together and the general mechanisms by which biocontrol strategies mitigate mycotoxin production in agriculture.

Technical Abstract: Biocontrol of the mycotoxin aflatoxin utilizes non-aflatoxigenic strains of Aspergillus flavus, which have variable success rates as biocontrol agents. One non-aflatoxigenic strain, NRRL 35739, is a notably poor biocontrol agent. Its growth in artificial cultures and on peanut kernels was found to be slower than that of two aflatoxigenic strains, and NRRL 35739 exhibited less sporulation when grown on peanuts. The non-aflatoxigenic strain did not greatly prevent aflatoxin accumulation. Comparison of the transcriptomes of aflatoxigenic and non-aflatoxigenic A. flavus strains AF36, AF70, NRRL 3357, NRRL 35739, and WRRL 1519 indicated that strain NRRL 35739 had increased relative expression of six heat shock and stress response proteins, with the genes having relative read counts in NRRL 35739 that were 25 to 410 times more than in the other four strains. These preliminary findings tracked with current thought that aflatoxin biocontrol efficacy is related to the ability of a non-aflatoxigenic strain to out-compete aflatoxigenic ones. The slower growth of NRRL 35739 might be due to lower stress tolerance or overexpression of stress response(s). Further study of NRRL 35739 is needed to refine our understanding of the genetic basis of competitiveness among A. flavus strains.